Factory rear locker

A friend of mine owns a wrecking yard and he got a wrecked double cab in with a factory rear locking axle, I have a chance to buy it for 750$. It’s got the 4.10 gear ratio and my truck is a 3.91. Would I need to swap the gears in the front axle or are these close enough to run?

 

you would need to swap a front differential with 4.10 gears as well

 

Why? It’s only a 5% difference in gear ratio. I’ve read several people running that and even more drastic with no issues.

 

You can probably get away with the front tires wanting to go farther than the rear tires for every turn of the driveshaft on loose ground. But nobody in their right mind would recommend it - on any remotely solid surface it'll bind and put unnecessary strain on the frame, driveshafts, axles, transfer case, etc.

Do yourself a favor and swap to 4.30's all around.

 

Even if you could get away with it, why take the risk? If it were a beater trail rig then thats one thing but if you need to rely on this truck I would get a matching front diff, shouldn't be hard to find a used one

 

I have heard of sand dragster running a higher ratio in the rear to help drive the front end down but unless you are only operating on very loose surfaces change the front as well. But if all you want to do is add a locker and or different ratio why change the whole axle?

 

Because the TRD e-lockers only fit the TRD axle housings (slightly different size than the non-TRD ones). Can't just install a TRD e-locker into a non-TRD axle, have to swap the entire axle instead.

TRD axles housings are 8" if I remember right, the non-TRD ones are 8.4".

 

if it's a good deal, buy it and get a front diff with factory gears for like $200

 

TBH I'd spend the $750 and get an aftermarket locker with your gear ratio
The e- lock axles are smaller anyways

 

I have a 4:10 front diff if you need one.

 

I call BS on the "no issues" statement.

No, who ever told you that, they just haven't noticed the issues, or don't care. Ever drive in a dry parking lot with your 4wd engaged? Yeah, it'd be like that, but driving straight down the road. 5% doesn't sound like a lot, but the simple fact is that your front and rear tires are moving at different speeds, and that's bad.

The 8.4" diff still has an 8" ring gear, so there's no real difference except the housing.

They just use the size difference to denote that the diffs are not interchangeable with the housings.